If you want to pull Apple’s version of the font and replace it with your older PostScript Type 1 versions of Helvetica—a common occurrence in production environments—you can’t. Unlike previous versions of OS X, Leopard won’t let you swap out one version for another.

This is an important issue for designers and prepress folks because there are slight differences between the TrueType versions of Helvetica that Apple ships with OS X and the PostScript Type 1 versions of Helvetica that many of us have used over the years. These differences can wreak havoc in print documents intended for production; for those people who don’t work in these environments, it’s not a big deal at all.

One solution is to move to Adobe’s OpenType version of the classic font, Helvetica LT. Of course, you can get it for a mere $2,599 (with 2,300 other OpenType fonts from the Adobe Type Library) on Adobe’s recently released Font Folio 11. If you’re on a tighter budget, you can also pick up Helvetica LT for a mere $29. 

It is possible to substitute the Apple Helvetica with your own Type 1 versions. Font management vendor Extensishas posted a PDF entitled “ Best Practices for Managing Fonts in in OS X,” which details a method for swapping Helvetica in Leopard: